Lubricant composition



3,110,673 LUBRICANT COMPGSITIQN George J. Benoit, in, San Anselmo,Calif., assign'or to Caiifornia Research Corporation, San Francisco,Calif,

a corporation of Delaware No Drawing. Filed Mar. 31, 1961, Ser. No.99,706 6 Claims. (Cl. 252F515) This invention is directed to a novellubricant composition. More particularly the invention is concerned witha superior new lubricant composition containing a pour point depressantashless detergent for use in internal combustion engines.

Detergents are commonly added to lubricant compositions to prevent thedeposit of solid materials on engine surfaces which come into contactwith the lubricant compositions. The deposits interfere with propercirculation of the lubricant composition in the engine and also act asabrasives which aggravate the Wearing of engine parts.

Many detergents presently employed in lubricant compositions are foundto contribute a substantial proportion of the deposits in modernengines. This is due to the fact that the detergents are commonlyemployed as metal salts and such metal salts form an ash deposit whenthe lubricant composition is consumed in the engine.

Lubricant compositions also contain pour point depressants to modify theflowing properties of the base oil so as to lower its pour point. Thetemperature at which a lubricant composition ceases to flow or pour iscalled its pour point and it is important that lubricant compositions becapable of flowing freely through oil lines and between moving engineparts at low temperatures in order to insure proper functioning of thelubricant composition in the engine.

In accordance with the present invention there is provided a superiornew ashless detergent lubricant composition having pour point depressingproperties in the lubricant composition comprising a major portion of anoil of lubricating viscosity and a minor portion sufficient to lower thepour point and enhance the detergent characteristics of the compositionof polyamide of fatty acids and polyalkylene polyamine in which thefatty acids are mixtures of from about 5 to about 30 mole percent ofstraight-chain fatty acids and from about 70 to about 95 mole percent ofbranched-chain fatty acids, said fatty acids containing from about 12 toabout 30 carbon atoms each and said polyalkylene polyamines containingfrom 2 to 6 alkylene amine units each, there being from 2 to 4 carbonatoms in each alkylene group, said polyamide containing frdm l to 3amine groups in addition to amide groups.

IThe lubricant composition of this invention as described above isunusually effective in depressing the pour point of the base oil oflubricating viscosity. The characteristically mixed fatty acid groups ofthe polyamides provide pour points which are surprisingly lower thansimilar oils containing polyamides characterized by either of the fattyacid groups alone. I

In adition to the pour depressing properties as mentioned above, thelubricant composition of the invention acts to prevent engine deposits.Since there is no metal component in the additive it is alsosubstantially free of ash-formingtendencies.

Thus is accordance with the present invention a single additive is foundto give both outstanding pour depressing and detergent properties incombination. This eliminates the necessity for multiple use of dilferentadditives which present problems of compatibility and tend to have anadverse effect on one another.

Detergent lubricating oil compositions containing the pour depressantashless detergent in accordance with 3,110,673 Patented Nov. 12, 1963the present invention are particularly satisfactory for use in 2-eyclegasoline engines. Such engines are becoming increasingly common inrecent years and are found in chain saws, lawn mowers, outboard marineengines and small cars or motor scooters.

The polyamides of the present invention may be conveniently illustratedby the following structural formula:

in which the alkylene group R contains from 2 to 4 carbon atoms, theradical R is hydrogen or an acyl group Ra( iwhich is derived from amixture of from about 5 to about 30 molepercent of straight-chain fattyacid and from about 70 to about 95 mole percent of branched-chain fattyacid, said fatty acids containing from about 12 to about 30 carbon atomsand n is an integer of from 1 to 5.

The polyamide of this invention is conveniently prepared according toknown methods by reacting the polyamine and the mixed fatty acids atconventional temperatures for the usual period of time required toamidify the amino groups of the polyalkylene polyamine. For presentpurposes temperatures in the range from about 250 F. to about 500 F. aresuitable. Usually the amiclification reaction requires from about 2 to10 hours. Means for removing water of condensation is employed andreduced pressures are desirable to effect amidification at the lowerreaction temperatures.

The proportions of fatty acids mixture and polyalkylene polyamine may besuch that the moles of the fatty acids are equal to the molarequivalents of amine groups in the polyalkylene polyamine. As alreadymentioned it is preferred that moles of fatty acid be on the average offrom about 1 to about 3 moles less than the number of available aminogroups in the polyamine.

The polyamide of the present invention which is formed by the reactionof fatty acid and polyalkylene polyamine is illustrated in the abovestructural formula as being in the nature of linear pol-yamide. Suchlinear polyamides undergo further condensation upon continued heating athigher temperatures with terminal amino groups to give either the monoorbis-imidazoline ring structure as illustrated by the following formula:

Suitable fatty acids for the preparation of the polyarnides of thepresent invention contain from- 12 to 30 carbon atoms as mentioned aboveand preferably from 16 to 20 carbon atoms. illustrative straight-chainacids include lauric acid, myristic acid, palmitic acid, stearic acid,eicosanoic acid, triacontanoic acid, etc.

Suitable branched-chain fatty acidsare those derived by synthesis suchas oxidation of olefins and polyolefins. Acidsderived from the OX0process are also suitable. Another source is polymerization ofunsaturated acids followed by hydrogenation. For example, an unsaturatedacid such as linoleic acid is dirnerized in accordance with typicalpolymerization techniques. 'During the reaction, part of the acidproduct is broken down to give an unsaturated mono acid lay-producthaving methyl chain branching. This product is hydrogenated resulting ina branched-chain saturated fatty acid of 18 carbon atoms.

For present purposes, it has been found that Emery Acid 3101 R isparticularly useful. This is monocarboxyli c acid having an equivalentweight of 310 and is sold commercially by the Emery Industries ofCincinnati, Ohio. It is described as a saturated lit-carbon atom fattyacid having methyl chain branching.

The polyalkylene polya-mines of the invention as mentioned above containfrom 2 to 6 alkylene amine units with from 2 to 4 carbon atoms in eachalkylene group. Illustrative amines include diethylenetriamine,triethylenetetraamine, tetraethylenepentaamine, hexaethyleneheptaamine,heptaethyleneoctaamine, tetrapropylenepentaamine, hexabutyleneheptaamineand the like. For present purposes triethylenetetraamine andtetraethylpentaamine are preferred for availability and efiectiveness ofthe polyamides prepared from them.

The following examples are illustrative of typical methods for preparingthe polyamide of the invention and of lubricant compositions containingit.

Example I In this example the polyamide of tetraethylenepentaamine and a10:90 mixture of straight and branchedchain acids is prepared.

A reaction vessel is charged with a mixture of 3.7 parts by Weight oftetraethylenepentaamine and 0.0002 part by weight of silicone foaminhibitor. The mixture is blanketed with nitrogen gas and heated toabout 250 F. A mixture of monocarboxylic acids amounting to about 18.2parts by Weight is introduced to the reaction vessel. This mixtureconsists of 10 mole percent stearic acid and 90 mole percent Emery 3101R acid. The mole ratio of tetraethylenepentaamine to total acid is about1 to 3. The reaction mixture is heated to about 300 F. for a period ofabout 1 hour and water of reaction is removed. Following this thereaction temperature is raised to about 400 F. at attmospheric pressurefor about one hour and then maintained at about 380 F. under a vacuumequivalent to 4 mm. of mercury pressure for a period of about 7 hours.

Example 11 This example illustrates the preparation of the polyamide oftetraethylenepentaamine and a 5:95 mixture of straight andbranched-chain acids.

To a 2-liter, 3-neck flask equipped with stirrer thermometer, refluxcondenser and means of heating, there is charged 189 g. oftetraethylenepentaamine (1.0 mole) and 0.01 g. of silicon foaminhibitor. The charge is heated under nitrogen to about 190 F. A mixtureof 42 g. stcaric acid (0.15 mole) and 873 g. Emery 3101 R acid (2.85moles) is then added. The contents of the flask are heated to 380 F. andthen put under a vacuum equivalent to about 20 mm. of mercury pressure.The reaction mixture is held under these conditions for about six hoursand then cooled. Then yield of product is quantitative.

Example III In this example the polyamide of tetraethylenepentaamine anda 20:80 mixture of straight and branched-chain acids is prepared.

In accordance with the procedure outlined in Example II above, 189 g. oftetraethylenepentaamine, 1 6 8 g. of stearic acid (20 mole percent oftotal acid) and 744 g. of Emery 3101 R acid (80 mole percent of totalacid) are reacted. A total of 3.0 moles of acid per mole oftetraethylenepentaamine is used. The yield of the product amounts toabout 100% on the basis of the reactants.

In general, excellent detergent and pour depressant properties can beimparted to lubricating oils by dissolving therein a quantity of fromabout 0.1 to 10% y weight of the polyamide of the type described above,although a preferred range is from about 1 to 5% y Weight; On the otherhand, since the polyamide of this invention is unusually compatible withmineral and other lubricating oils in substanti lly all proportions, asmuch a as of the present polyamide additives can be dissolved in asuitable lubricating oil for the purpose of preparing a concentratecapable of dilution with lubricating oils and the like to prepare thefinal lubricant composition. Such concentrates, which may also containother additives in desired amounts, and which normally contain at least1 0% of the polyanride, comprise a convenient method for handling thepolyamide and may be used as a compounding agent for lubricants ingeneral.

The polyamide additives of this invention can be used with good effectin the case of any one of a wide variety of oils of lubricatingviscosity, or of blends of such oils. Thus, the base oil can be arefined Pennsylvania or other paraffin base oil, a refined naphthenicbase oil, or a synthetic hydrocarbon or non-hydrocarbon oil oflubricating viscosity. As synthetic oils there can be mentionedalkylated waxes similar alkylated hydrocarbons of relatively highmolecular Weight, hydrogenated polymers of hydrocarbons, and thecondensation products of chlorinated alkyl hydrocarbons with arylcompounds. Other suitable oils are those which are obtained bypolymerization of lower molecular weight alkylene oxides such aspropylene and/ or ethylene oxide. Still other synthetic oils areobtained by etherification and/or esterification of the hydroxy groupsin alkylene oxide polymers, such as, for example, the acetate of the2-ethylhexaaol-initiated polymer of propylene oxide. Other importantclasses of synthetic oils include the various esters as, for example,di- -(2-ethylhexyl)sebacate, tricresyl phosphate and silicate esters. Ifdesired, the oil can be a mixture of mineral and synthetic oils. Forpresent purposes the polyamide of this invention finds its greatestutility in waxy mineral lubricating oils and such compositions aretherefore preferred.

While satisfactory lubricant compositions can be obtained by adding tothe base oil employed only one or more of the polyamide additives of thetype described above, it also falls within the purview of this inventionto provide lubricant compositions which containnot only such polyamidesbut also other additives such as oiliness, and extreme pressure agents,anti-oxidants, corrosion inhibiting agents, blooming agents, thickeningagents and/ or compounds for enhancing the temperature-viscositycharacteristics of the oil.

Illustrative lubricant compositions of the above type containing thepolyamide additives of the invention in combination with other agentsmay include, for example, from about 0.1 to 10% by weight of alkalineearth metal higher alkylphenate detergent and Wear reducing agents 7such as calcium alkyiphenates having an average of approximately 14carbon atoms in the alkyl group as well as organic thiophosphatecorrosion and high. temperature oxidation inhibitors such as thereaction product of pinene and P 8 and the bivalent metaldithiophosphate and zinc tetradecylphenyl dithiophosphate in amounts. offrom about 0.1 to 10% by weight of the composition.Temperature-viscosity improving agents which may be em ployed in thecompositions, usually in amounts of from about 1 to 10% by Weight,include by Way of example the homopolymers of alkyl methacrylates suchas the dodecyl methacrylate polymers known to the trade as Acryloid 710and Acryloid 763, products of Rohrn & Haas Company, and high molecularweight butene polymers such as Paratone ENl 15P, a product of the EnjayCorn pany.

The polyamide additives of the invention as described above areevaluated as pour depressants in lubricating oils in a number of tests.The base oil is a solvent-refined waxy SAE 30 mineral lubricating oilhaving a pour point of +10 F. The results of the tests are set out inthe following table. For convenience a typical polyarnine, namely,tetraethylenepentaamine is selected and the illustrative acids chosenare stearic acid and Emery 3101 R acid. The pour point tests areperformed in accordance with ASTM method D97. The sample is maintainedat a temperature of 115 F. or lower for at least 24 hours prior to thetest. The sample is then cooled systematically under quiescentconditions and observed at intervals of 5 F. The pour point is thelowest temperature at which the oil flows when the container is tilted.

Stean'c acid, mole percent: Pour point or" oil, F.

As shown by the test results of the above table the polyamide additiveof this invention imparts surprisingly improved pour pointcharacteristics to lubricant compositions compared to similarcompositions containing polyamides of conventional types.

It is further evident that the improved pour point characteristics ofthe polyamides of this invention are due to the particular proportionsof straight-chain fatty acid and branched-chain fatty acid and thatproportions Within the preferred ranges provide pour ponits which areunpredictably lower than mixtures of other proportions of acids.

I claim:

1. A lubricant composition comprising a major proportion of a waxymineral lubricating oil and a minor proportion sufiicient to enhance thepour point characteristics of the composition of a polyamide of fattyacids and tetraethylenepentaamine in which the fatty acids are mixturesof from about 5 to about 30 mole percent of straight-chain fatty acidsand of from about to about 95 mole percent of branched-chain fattyacids, said fatty acids containing from about 12 to about 30 carbonatoms each and said polyamide containing from about 1 to about 3 aminegroups in addition to amide groups.

2. A lubricant composition comprising a major proportion of a waxymineral lubricating oil and a minor proportion sufficient to enhance thepour point characteristics of the composition of a polyarnide of fattyacids and tetraethylenepentaamine in which the fatty acids are mixturesof from about 5 to about 30 mole percent of stearic acid and from about70 to about '95 mole percent of methyl branched-chain fatty acidcontaining about 18 carbon atoms, said polyamides containing from 1 to 3amine groups in addition to amide groups.

3. A lubricant composition comprising a major propotion of a Waxymineral lubricating oil and from about 0.1 to about 10% by Weight of apolyamide of fatty acids and tetraethylenepentaamine in which the fattyacids are mixtures of from about 5 to about 30 mole percent of stearicacid and from about 70 to about 95 mole percent of methyl branched-chainfatty acid containing about 18 carbon atoms, said polyamide containingfrom 1 to 3 amine groups in addition to amide groups.

4. A lubricant composition comprising a major proportion of a waxymineral lubricating oil and from about 0.1 to about 10% by weight of apolyamide of fatty acids and tetraethylenepentaamine in which the fattyacids are mixtures of from about 10 mole percent of stearic acid andfrom about mole percent of methyl branched-chain fatty acid acidcontaining about 18 carbon atoms, said polyamide containing from 1 to 3amine groups in addition to amide groups.

5. A lubricant composition comprising a major proportion or" a waxymineral lubricating oil and from about 0.1 to about 110% by weight of apolyamide of fatty acids and tetraethylenepentaamine in which the fattyacids are mixtures of from about 5 mole percent of stearic acid and fromabout mole percent of methyl branched-chain fatty acid containing about18 carbon atoms, said polyamide containing from 1 to 3 amine groups inaddition to amide groups.

6. A lubricant composition comprising a major proportion of a waxymineral lubricating oil and from about 0.1 to about 10% by weight of apolyamide of fatty acids and tetraethylenepentaamine in which the fattyacids are mixtures of from about 20 mole percent of stearic acid andfrom about 80 mole percent of methyl branched-chain fatty acidcontaining about 18 carbon atoms, said polyamide containing from 1 to 3m'ne groups in addition to amide groups.

References Cited in the file of this patent UNITED STATES PATENTS2,622,067 White et al Dec. 16, 1952 2,693,468 Blair Nov. 2, 19542,713,583 Smith July 19, 1955 2,736,658 Pfohl et al. Feb. 28, 1956

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR PROPORTION OF A WAXYMINERAL LUBRICATING OIL AND A MINOR PROPORTION SUFFICIENT TO ENHANCE THEPOUR POINT CHARACTERISTICS OF THE COMPOSITION OF A POLYAMIDE OF FATTYACIDS AND TETRAETHYLENEPENTAAMINE IN WHICH THE FATTY ACIDS ARE MIXTURESOF FROM ABOUT 5 TO ABOUT 30 MOLE PERCENT OF STRAIGHT-CHAIN FATTY ACIDSAND OF FROM ABOUT 70 TO ABOUT 95 MOLE PERCENT OF BRANCHED-CHAIN FATTYACIDS, SAID FATTY ACIDS CONTAINING FROM ABOUT 12 TO ABOUT 30 CARBONATOMS EACH AND SAID POLYAMIDE CONTAINING FROM ABOUT 1 TO ABOUT 3 AMINEGROUPS IN ADDITION TO AMIDE GROUPS.